Sunday, May 31, 2015

Mulch: How to Use it & Prevent Problems

How to Calculate the Amount of Mulch Needed
To determine how many cubic feet of mulch is needed, you need to calculate the surface area and the desired depth of coverage. There are 27 cubic feet in a cubic yard. One cubic yard will cover a 324-square-foot area with an inch of mulch. Figure out the square footage of your bed, that is the width times the length for square or rectangular shaped beds. The square footage of a circular bed is the distance from the middle of the circle to the outside multiplied by itself and then multi- plied by 3.14 (which is pi). Multiply your square footage by the depth desired (in inches) and divide by 324 square feet. This will tell you how many cubic yards you will need.

Mulch Toxicity: Though mulch benefits plants, “sour” mulch can quickly damage plant tissue and lower the soil pH causing injury or death. Bedding and low-growing woody plants are most easily damaged. Symptoms include yellowing of the leaf margins, scorching or dropping of leaves and occasionally entire plant death. Although it may be several days before symptoms appear, spreading sour mulch can damage plants immediately.

Sour or “acid” mulch is caused by poor handling or storing of mulch resulting in anaerobic (without air) conditions. Mulch piles need to “breathe” to prevent anaerobic conditions from occurring. In the absence of air, microbes in the mulch (mostly bacteria) produce toxic substances such as methanol, acetic acid, ammonia gas, and hydrogen sulfide gas.

Sour mulch smells like vinegar, ammonia, sulfur or silage. Good mulch smells like freshly cut wood or has the earthy smell of a good garden soil. Another way to determine if mulch is sour is to test its pH. Toxic mulch will have a pH of 1.8 to 2.5.

To prevent mulch from turning sour or to cure sour mulch, you need to turn your pile once or twice a month, more frequently if the pile is very wet. Do not let the pile get larger than 4 feet thick in any dimension if you are not turning the pile regularly. A good aeration will eliminate the toxic com- pounds in 24 hours, but to be safe allow three days.

Slime Molds: Slime molds are fungus-like organisms that can be a nuisance in mulch. They typically appear suddenly during warm, damp weather. The resulting masses may be several inches to a foot or more in diameter and vary in color, including bright yellow or orange. They are unsightly but harm- less, feeding on decaying organic matter such as that found in new hardwood mulch. No pesticides are recommended. Simply scoop up with a shovel and remove.

Matted Mulch: When thick layers of dry mulch are applied or existing mulch dries, some nuisance fungi can grow, forming a mat of mycelium (a mass of fine threadlike structures that make up the body of the fungus). The mycelial mat is hydrophobic (repels water). As a result, the mulch is not easily penetrated by water, which can prevent plants from receiving adequate water. Newly installed mulch should be watered to prevent this problem. If existing mulch is matted, break apart the matted layers with a rake or claw cultivator.

The Artillery Fungus: Occasionally, microorganisms in mulches can become a nuisance. The shotgun or artillery fungus (Sphaerobolus) may cause serious problems. While it delays the mulch, it also produces fruiting structures that resemble tiny cream or orange-brown cups that hold a spore mass resembling a tiny black egg (1/10 inch in diameter). This fungus shoots these spore masses high into the air. They stick to any surface and resemble small tar spots on leaves of plants, on cars or on siding of homes. They are very difficult to remove. To avoid damage to cars and houses do not use mulches that contain cellulose (wood). Use pure bark mulches, especially pine, or if the mulch is already in place, cover the hardwood mulch with pine needles.

Stinkhorn Fungi: Stinkhorn fungi, such as Mutinus caninus and M. elegans, can colonize hardwood bark mulch. The fruiting bodies or mushrooms often come up in the fall and exude a very unpleasant odor. Scoop up and dispose of the mushroom as soon as they appear. Consider replacement of hardwood bark mulch, which contains a lot of wood, with an- other choice, such as pine needles, pine bark, or a composted mulch.

Shotgun Fungus
What are some solutions to Sphaerobolus stellatus growing in mulch? – Pennsylvania
Researchers don’t know a great deal about this organism, which is also known as the shotgun fungi. However, it apparently is becoming a more prevalent problem in many regions of the United States and Canada. Extension horticulturist Dr. Larry Kuhns is leading a study at the Pennsylvania State University with hopes of learning enough about shotgun fungus to offer practical solutions.

Sphaerobolus thrives in moist wood mulch and produces its spores in spring and fall. While this fungus does not seem to harm landscape ornamentals, it can create serious aesthetic problems when it sporulates and can stain walls, automobiles or other objects. The problem stems from the fact that the fungus “fires” its spore masses into the air. Wherever they land, they stick with incredible tenacity- the spots resemble fly specks- and defy almost every effort to remove them. These spore masses may not be noticeable at first, but as they accumulate over several years, they create a splattering effect similar to black paint sprayed through a partially clogged nozzle. Kuhns is aware of instances where the problem was severe enough to prompt insurance claims and even lawsuits against the landscapers that installed the mulch.

According to Kuhns, the rising occurrence of shotgun fungus may relate to the increasing wood content of many mulches that groundscare professionals apply to landscapes. Woody material, as opposed to bark, is the food source of this fungus. Several possible factors may be contributing to this increase in wood content. “Bark” mulch- more than ever- often contains more wood than bark. Further, waste wood- pallets, for example, is increasingly being converted to mulch for landscape use. Many landfills now prohibit landscape waster and much of this is converted to mulch as well. Combined with greater use of mulch generally, the increasing wood content of land- scape mulches may be promoting the spread of Sphaerobolus. As Kuhns points out, however, much of what is “known” about Sphaerobolus is based on educated guessing.

At this point, authorities can offer few practical solutions. Applying a layer of bark mulch over the top of Sphaerobolus-infested wood mulch may help block the spore masses from reaching vulnerable surfaces. Ensuring any mulch you use near visible surfaces primarily is composed of bark- not wood- should also help. Once staining has occurred, there isn’t much you can do. That’s why finding a way to remove the spore stains from various surfaces is one of Kuhn’s research goals.

Research Update: A new study reaffirms the benefits of mulching trees
Mulching tree bases may be one situation where you can have too much of a good thing. Because researchers have proven that mulching offers many benefits, some grounds managers get carried away, sometimes applying excessive amounts to depths greater than 50 centimeters (20 inches). This practice has prompted several studies about mulching, a few of which reported detrimental effects such as oxygen deprivation or root rot. To test these results, researchers at Cornell University looked at the effects various thicknesses of mulch had on young trees.

The investigators used chipped pine mulch and shredded hardwood mulch around young trees—Pinus strobus and Quer- cus palustris—in depths ranging from 7.5 to 25 centimeters (3 to 10 inches). After 2 years, the results affirmed many of the beneficial effects of mulching. The mulch improved soil-moisture retention, moderated soil-temperature swings and sup- pressed weed growth. Moreover, the mulch did not significantly reduce oxygen levels, even where the mulch was as deep as 25 centimeters.

However, the study yielded other, less-expected results as well. Weed suppression improved with increasing mulch depth, even up to 25 centimeters. Also, the mulch did not alter pH or nitrate levels in the underlying soils. Interestingly, one of the possible drawbacks of mulching- trunk infection by pathogenic fungi or canker-causing agents- did not occur in this study. The investigators specifically looked for infection and even created wounds as entry sites for pathogens. Possibly, no appropriate pathogens were present in the mulch, but this is an encouraging result nevertheless.

A potential problem with using thicker mulch layers (15 to 25 centimeters in this study) stems from the fact that this may delay the warming of soil in spring, which could slow root growth. However, this study reaffirms that the often-recommended depth of 7.5 centimeters provides optimum benefits with few, if any, negative effects.

Rabbit Resistent Plants

No plants can be said to be rabbit proof. Rabbits eat virtually anything, and most plants are especially vulnerable when young. However, there are some plants which rabbits generally avoid. We have drawn on several sources to provide the suggestions listed here.

In general, rabbits are discouraged by very aromatic plants, prickles and spines, and tough, leathery leaves.

Blue Mist Spirea 
Russian Olive 
Russian Sage 
St. John’s Wort 

Perennials & Annuals
African Daisy 
Autumn Cross 
Geranium (Perennial)
Lead Plant 
Lily of the Valley 
Red Hot Poker 
Sea Holly 
Solomon’s Seal 

18 Reasons to Plant a Tree

1. Alleviating the “Greenhouse Effect,” trees act as carbon “sinks.”
  • One acre of new forest will sequester about 2.5 tons of carbon annually. Trees can absorb CO2 at the rate of 13 pounds/tree/year. Trees reach their most productive stage of carbon storage at about 10 years.
  • In its “Reforesting the Earth” paper, the Worldwatch Institute estimated that our planet needs at least 321 mil- lion acres planted to trees
  • just to restore and maintain the productivity of soil and water resources, meet industrial and fuel-wood needs in the third world, and annually remove from the atmosphere roughly 780 million tons of carbon as the trees grow. This 780 million tons represents the removal of about 25 percent of the 2.9 billion tons of carbon currently going into the earth’s atmosphere.
  • Planting 100 million trees could reduce the amount of carbon by an estimated 18 million tons per year and, at the same time, save American consumers $4 billion each year on utility bills.
  • For every ton of new wood that grows, about 1.5 tons of CO2 are removed from the air, and 1.07 tons of life-giving oxygen is produced. During a 50-year life span, one tree will generate $30,000 in oxygen, recycle $35,000 worth of water, and clean up $60,000 worth of air pollution—or $125,000 total per tree without including any other values!

2. Prevents or reduces soil erosion and water pollution.
3. Helps recharge ground water and sustain stream flow.
4. Properly placed screens of trees and shrubs significantly decrease noise pollution along busy
thoroughfares and intersections. 5. Screen unsightly views.
6. Soften harsh outlines of buildings.
7. Depending on location, species, size, and condition, shade from trees can reduce utility bills for air conditioning in residential and commercial buildings by 15–50 percent. Trees, through their shade and transpiration, provide natural “low-tech” cooling that means less need to build additional dams, power plants, and nuclear generators.
8. Windbreaks around homes can be shields against wind and snow, and heating
costs can be reduced by as much as 30 percent.
9. Shade from trees cools hot streets and parking lots. Cities are “heat islands” that are 5–9 degrees hotter than surrounding areas. And cities spread each year.
10. Trees and shrubs properly placed and cared for on a residential or commercial lot can significantly increase property values.
11. Trees also provide nutmeats (walnuts, pecans, and hickory), fruit (plum, peaches, apples, and pears), berries for jams and jellies (chokeberry and buffalo berry) and maple syrup.
12. Trees add beauty and grace to any community setting. They make life more enjoyable, peaceful, relaxing, and offer a rich inheritance for future generations.
13. Trees give people a multitude of recreational opportunities and provide habitat for wildlife.
14. Trees along rivers, streams, and lakes reduce water temperatures by their shade, prevent or reduce bank erosion and silt, and provide hiding places for improving fisheries habitat.
15. They provide brilliant colors to landscapes in the fall. After the leaves drop to the ground and are raked, they provide excellent mulch for flowerbeds and gardens as well as exercise for people.
16. Police officers believe that trees and landscaping can instill community pride and help cool tempers that sometimes erupt during “long, hot summers.”
17. Trees are valuable as commemoratives of deceased loved ones and for passing on something of value to future generations.
18. Finally, many people enjoy planting and caring for trees simply because they like to see them grow.

Sources: Glenn Roloff USDA Forest Service – Northern Region Missoula, Montana

Wednesday, May 20, 2015

The New York Botanical Garden: June Gardening Tips

Chores and Maintenance

- Continue to cultivate planting beds to remove weeds
- Continue to dig and divide early-blooming perennials after flowering
Water as necessary
- Continue to mulch planting beds
- Set supports for floppy plants, vines, and vegetables
- Deadhead rhododendrons, lilacs, and perennials after flowering
- Add to, aerate, and moisten compost pile to speed decomposition
- Continue to check for pests and other problems, and treat as necessary
- Mow lawns regularly to keep grass at 2 to 2 1/2" height
- Leave grass clippings on lawn to improve availability of nitrogen
- Water lawns if there is less than 1" of rain per week
- Harvest cool-weather lettuce, radishes, and scallions
- Begin to spray roses every week with baking soda solution* to protect against black spot disease
- Continue application of deer repellents
* Cornell University formula consists of: 3 tsp. baking soda, 2 1/2tbs. summer-weight horticultural oil, mixed with 1 gallon of water.


- Complete moving self-sown annuals and perennials to desired location
- Sow seeds of fast-growing annuals like marigolds, zinnias, and cosmos directly in the garden
- Sow seeds of heat-tolerant vegetables
- Continue to plant and transplant perennials, weather and soil conditions permitting
- Finish planting summer annuals
- Complete planting summer-flowering bulbs such as cannas, gladiolas, and dahlias
- Plant caladium and tuberous begonias in shady spots


- Continue to prune all plant material to remove any diseased, dead, weak, or crossing branches
- Complete pruning early spring-flowering shrubs
- Prune evergreens and evergreen hedges into early summer
- Continue deadheading roses
- Fertilize roses after peak bloom
- Complete fertilizing spring-flowering bulbs
- Fertilize annuals and container plants
- Fertilize vegetables